Re: [PATCH] KVM: ioapic: fix NULL deref ioapic->lock

From: Wanpeng Li <kernellwp@gmail.com>
To: Paolo Bonzini <pbonzini@redhat.com>
Cc: "David Hildenbrand" <david@redhat.com>,
	"Dmitry Vyukov" <dvyukov@google.com>,
	LKML <linux-kernel@vger.kernel.org>,
	"KVM list" <kvm@vger.kernel.org>,
	"Radim Krčmář" <rkrcmar@redhat.com>,
	"Wanpeng Li" <wanpeng.li@hotmail.com>
Subject: Re: [PATCH] KVM: ioapic: fix NULL deref ioapic->lock
Date: Wed, 4 Jan 2017 06:03:52 +0800	[thread overview]
Message-ID: <CANRm+Cy8mdqM-i_MBHxY6=Nbf=wdTN+k_2pcjEZc0BOZQzPwGg@mail.gmail.com> (raw)
In-Reply-To: <3f0b0708-0dda-85d4-a0a0-2d532d46db18@redhat.com>

2017-01-04 1:23 GMT+08:00 Paolo Bonzini <pbonzini@redhat.com>:
>
>
> On 03/01/2017 13:06, David Hildenbrand wrote:
>>>
>>>      switch (cap->cap) {
>>>      case KVM_CAP_HYPERV_SYNIC:
>>> -        return kvm_hv_activate_synic(vcpu);
>>> +        if (!irqchip_in_kernel(vcpu->kvm))
>>> +            return -EINVAL;
>>> +        else
>>
>> You can simply drop the else and return directly.
>>
>> Can't really say if this is the right fix, my first thought was that
>> a request has been set although it should never have been set for
>> that VCPU. Maybe that is an effect of synic being activated
>> (because synic code unconditionally later on sets the request).
>>
>> Fixing the cause of the request seems better than fixing up the result.
>
> Yes, I agree.  Wanpeng's second patch is fine.

Thanks Paolo, I will send out a formal one soon.

Regards,
Wanpeng Li